linux-kernel - [PATCH v1] clocksource: Sigma Designs Tango 27 MHz xtal

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Date:	Tue, 6 Oct 2015 17:10:20 +0200
From:	Marc Gonzalez <marc_gonzalez@...madesigns.com>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
CC:	LKML <linux-kernel@...r.kernel.org>,
	Mans Rullgard <mans@...sr.com>, Mason <slash.tmp@...e.fr>
Subject: [PATCH v1] clocksource: Sigma Designs Tango 27 MHz xtal

Date: Tue, 6 Oct 2015 16:49:28 +0200
Subject: [PATCH] clocksource: Sigma Designs Tango 27 MHz xtal

Sigma Designs Tango platforms provide a 27 MHz crystal oscillator.
Use it for clocksource, sched_clock, and delay_timer.

Signed-off-by: Marc Gonzalez <marc_gonzalez@...madesigns.com>
---
 drivers/clocksource/Makefile     |  1 +
 drivers/clocksource/tango_xtal.c | 46 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)
 create mode 100644 drivers/clocksource/tango_xtal.c

diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index f228354961ca..46e405673d75 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_ARCH_CLPS711X)	+= clps711x-timer.o
 obj-$(CONFIG_ARCH_ATLAS7)	+= timer-atlas7.o
 obj-$(CONFIG_ARCH_MOXART)	+= moxart_timer.o
 obj-$(CONFIG_ARCH_MXS)		+= mxs_timer.o
+obj-$(CONFIG_ARCH_TANGOX)	+= tango_xtal.o
 obj-$(CONFIG_CLKSRC_PXA)	+= pxa_timer.o
 obj-$(CONFIG_ARCH_PRIMA2)	+= timer-prima2.o
 obj-$(CONFIG_ARCH_U300)		+= timer-u300.o
diff --git a/drivers/clocksource/tango_xtal.c b/drivers/clocksource/tango_xtal.c
new file mode 100644
index 000000000000..0f2fb293ab75
--- /dev/null
+++ b/drivers/clocksource/tango_xtal.c
@@ -0,0 +1,46 @@
+#include <linux/clocksource.h>
+#include <linux/sched_clock.h>
+#include <linux/of_address.h>
+#include <linux/delay.h>
+#include <linux/clk.h>
+
+static void __iomem *xtal_in_cnt;
+static struct delay_timer delay_timer;
+
+static unsigned long read_xtal_counter(void)
+{
+	return readl_relaxed(xtal_in_cnt);
+}
+
+static u64 read_sched_clock(void)
+{
+	return read_xtal_counter();
+}
+
+static cycle_t read_clocksource(struct clocksource *cs)
+{
+	return read_xtal_counter();
+}
+
+static struct clocksource tango_xtal = {
+	.name	= "tango-xtal",
+	.rating	= 350,
+	.read	= read_clocksource,
+	.mask	= CLOCKSOURCE_MASK(32),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static void __init tango_clocksource_init(struct device_node *np)
+{
+	struct clk *clk = of_clk_get(np, 0);
+	unsigned int xtal_freq = clk_get_rate(clk);
+	xtal_in_cnt = of_iomap(np, 0);
+
+	delay_timer.freq = xtal_freq;
+	delay_timer.read_current_timer = read_xtal_counter;
+	register_current_timer_delay(&delay_timer);
+	sched_clock_register(read_sched_clock, 32, xtal_freq);
+	clocksource_register_hz(&tango_xtal, xtal_freq);
+}
+
+CLOCKSOURCE_OF_DECLARE(tango, "sigma,tick-counter", tango_clocksource_init);
-- 
2.4.5

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